Automatic steering for dirigible craft



Oct. 8, 1929. E. A. sPERRY, JR 1,730,951

'AUTOIATIC STEERING FOR DIRIGIBLE CRAFT filed July 7, 1922 4sheets-sheet l1 www-ff] I:

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Oct. 8, 1929. E. A. sPERRY, JR I UToI-TUSTEERING FOR DIRIGIBLE CRAFTFiled .my 7. 1922 4 sneefsneet 2` 3&1 zum' Oct. 8, 1929. E. A. sPERY,'JR1,730,951

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97 ss sa al 8. 4. I l l I l l I I I I I I I I I I I I I I l I I I I I lI Patented Oct. 8, 1929 UNITED sra'rlasA APfATl-:NT OFFICE Emma asPEnRY, Ja., or BROOKLYN, NEWYORK, assreNon., BY masNE AssIGNQ MENTS, TosrEnnY GYROSCOPECOMPANY, INC., A CORPORATION OF NEW Yom:

AUTOMATIC STEERING For. DIRIGIBLE 'CRAFT l Application med July 7, 1922.serial'No. 573,280.

This invention relates to the navigation of all kinds of craft, moreespeciallyl to the steering of dirigible craft, such as vessels, tor`pedoes and aeroplames, which are guided by means of a` rudder. Moreparticularly, this invention relates tonavigation of such craft byautomaticmeans which operate to hold a vessel upon its course .andpreventyawing movements by introducing counteracting forces uponincipient changes in heading of the craft.

This invention has for one of' its objects keeping a ship on its truecourse by attacking yaw in the form of an automatic device wherebV amean helm position is not only constantly vsought and found, butre-established for every wind, tide and'current condition through whichthe craft is traveling. By mean helm position is meant the position ofrest of the rudder which varies fromthe trueY central position due tosuch causes as variationin the revolutions of the propellers in multipleshown what I now consider to be a preferred screw ships, weather,direction of tides,

winds, current, etc. Any of these forces may l operate to turn the craftconstantly in. one direction resulting in a small but appreclabledeviation from the true or set course. To

bring the craft back to its course would necessitate swinging the rudderoutwardly through a comparatively large angular'distance. As the shipreached its course, the rudder would be returned to initial position,

, but immediately the forces mentioned above would again turn the craftofi' its course to substantially thev same extent, necessitatingswinging the rudder outwardly a second time. A large yawing movementthus takes place. This vprocess would be continuous as long as theforces were present, unless the mean position of the rudder were re-setwith respect to the ship to a new, or virtual, central position whichwould neutralize the hereinbefore mentioned forces. Having once foundthe mean helm, or virtual center, position, it will be apparent that asubstantlal amount `of yaw has been eliminated, 'and the yaw which takesplace can be much more quickly 'attacked and corrected from the new baseline of the rudder. Thisv new mean position,

of the rudder allows the yaw to be corrected and incipient changes ofheading to be taken care of with less'frequent shifts of the rudder, aswell as less departure from the new base-line or `virtual center, thuseliminating a large amount of drag and retardation upon the forwardprogress of the ship.

-I-Iither-to, the setting of the mean helm position was left entirely-tothe experience of the helmsman or quartermaster. Consciously orunconsciously, themore experienced helmsof this invention.

Other objects and advantages will be in part obvious and in partspecifically pointed out in the speciication.-

Referring to the drawings wherein I have embodiment ot my invention,

Fig. l' is a front elevation of that portion of the steering apparatus,which is adapted to be placed in the pilot house of a vessel.l

Fig. 2 is a plan view of a master course controller shown in Fig. I.

Fig. 3 is a verticalsection through thev master course controller.

Fig. 4 is awiring diagram of the course control mechanism. I

Fig. 5 is a plan view of the automatic helm positioning means.

Fig. 6 1s a vertical section through the device shown in Fig. 5.

Fig. 7 is a front diagrammatic view-of the contact-'controlling meansforming part of the device in Fig. 5.

Fig. 8 is a plan view of aeportion of the device of Fig. 5, showing theparts indifferent operative relation to set the rudder for helln.

Fig. 9 is aplurality of graphs or records illustrating the principles ofnavigation em bodied in this invention.

Referring to F ig's. 1 to 3', I locate, preferably .in the pilot-houseof theship, a master controller. 1 from whichthe rudder is automaticallycontrolled. The system of coursecontrol by the mechanism of F igs.. 1 to4 inclusive is fully set forth and claimed in the copending applicationof Chester B. Mills, Serial No. 569,295, Automatic steering fordirigible craft, and for a more complete description, reference shouldbe had thereto,

but it will be described here briefly. Said master controller is shownmounted on a stand 3 and performs the functions both of a steeringrepeater compass and a master controller, the standard repeater compasscard 10 cooperating with the settable course indicator 11. Theindicator, or pointer 11, is mounted upon a shaft 12 concentric withcard 10, controlled from a repeater motor 13. The entire mechanism isenclosed in a casing 9 having the usual glass cover 14 and bezel 15. Thecard is rotated by the motor 13 through gears 16, 17 to rotate shaft 18and gear 19 thereon, gear 19 mashing with ,gear 20 on a bushing 21jounralled in a. partition plate 22, said card being fixed to the upperend of said bushing.

To set the pointer relative to the repeater card the usual handle 30 maybe provided which operates by means of bevel gear 31 a differentialcomprising upper gear 32 and lower gears 33, 34, the gears 31 and 34mesh-` ing with gears 35 and 36 of a planetary member 37 fixed to shaft18. Since shaft. 18 is rotated by the repeater motor, operation ofhandle 30 will rotate gears 35 and 36 about their axes to rotate gear 32and gear 40 fixed thereto, said gear 40 meshing with gear 41 fixed tothe pointer shaft 12. Fixed to gear 32 is a trolley 50 meshing withcontact strips 51,

{i2-arranged in the formy of rings, here shown l positioned to one sideof the casing. It will be obvious that when a new course is set byhandle 30, or when the ship turns off its course, so that trolley 5() isrotated by the repeatermotor along the contact strips 51, or 52, thereis set in oper-ation the following means to move the ship to a newcourse or bring it back.- after it has moved offy its course. Y A' Anydevitation of the ship from its course will cause rotation of gear 32,and hence, of the card 10 and the trolley 50. Referringl to Fig. 4, itwill be .observed that the trolley 50 is in the form of a lever whichcarries three contacts 68, 69 andV 70, the first two upon one armthereof and Athe` last upon the other arm. Contacts 68`and 7 0 engagecontact strips 51, 52, 71, 72, 73 and` 74 of a contact ring, whileContact 69 engages a separate contact 7 6. The operation of the deviceis as follows: L

' Oase 1.-Assume slight yawing movement in a clockwise directioninsuflicient to move contact 68 olf insulation 54 between contact strips51 and 52. Acircuit is then established from main lead'140, contacts 69and 7 6, to an auxiliary control `device 25. Said device comprisesbrushes 26, 27, 28 and 29, controlled from a repeater motor 39 similarto motor 13, and cooperating with a contactor ring or commutator 38.Said commutator has live segments 43 and 44, the former cooperating withbrushes 26 and 27, and the latter cooperatino' with brushes 28 and 29.All of said brushes normally contact with insulated strips 45.

So that in the'case here discussed, brushv 28 engages contact 44, andthe circuit continues through said contacts 80, 81, and relay coil 82,closing a circuit through coil 83 of a motor 84 to drive the rudder inclockwise direction and move the ship counterclockwise to counteract theyaw. The end of the rudder 46 is provided with a block 85 which closes aset of contacts 86, when said rudder moves as desired, to break thecircuit through field coil 83 by 'energizing relay 80. The rudder isheld in this position until the ship turns back counterclockwisesufliciently to move brush 29 into engagement with contact 44 toestablish a circuit through relay cone. tacts 87, 88 and relay coil 89which closes a circuit through oppositely-wound coil 90 of motor 84 todrive the rudder counterclockwise and turn the ship clockwise. When therudder engages contacts 91, it breaks the circuit through coil 90 byenergizin relay 87. These small oscillations of the ru der betweencontacts 86 and 91 are thus continued during the small yawing movementsof the ship to counteract such movements. The relays 82 and '89 arenormally open, and when closed, serve to close the circuit through themotor from main lead 140 to main lead 141. f

Oase Z-Assume greater deviations of the ship so that contact 68 engagescontact 51 oi 52, contact 70 does not move out of engagement withcontact 74, and contact 69 does not move out of engagement with Contact76. If

the ship yaws clockwise, a circuit is established from main lead 140,contacts 68, 51,43, 26, relays 81 and 82 to coil 83 of the motor, andanother circuit from contacts 69, 76, 44,

28, relays 80, 81, 82, also to coil 83 tol drive the rudder clockwiseand turn the ship counterclockwise to counteract the yaw. When the irudder closes contacts 92, it forms a circuit including contacts 70 and74 to break the circuit through coil 83 by energizing relay 81.

Trolley 5() rotates through the full angle of deviation, but thecommutator of the auxiliary control device 25 is limited to a very smallmovement by stops (not shown) and a slipfriction connection between thecommutator and its shaft, which permits the shaft to con-l tinue torotate after the commutator has been stopped.

l Because of the smallmovement of the coinmutator, as soon as the shipstarts to turn clockwise, brush 26 moves olf contact 43 while p contact68 is still on contact 51, and brush 28 I agesmovesoff `contact 44.Brush 29 now en contact 44 to establish a circuit throug the i tion, thelower set of relays is lower relays andi-coil 90 to drive the rudderuntil the rudder'engages contacts 93. AAs

-soonas the ship starts to turn back, the up er `set of relays isenergized to return the rud er,

until the latter engages contacts 86 to energize relay 80. f

Uase 3.-Assume in case 2 that the deviations are suiiicient to movecontact 70 into en -l -gagement with contact 72 or 73. The operationwould be the saine as in' case 2. except y that the'circuits'whichcontrol the limiting as it nears-its Y tions '3, to swing' I ,themomentum of the positions of the rudderwould now be from contact 70,contact 72 or 73, to contacts 94or 95 instead o 92 and 93, greaterswinging ofthe rudder corresponding to the gieaterangle of deviation ofthe ship.

Gase gif-'Assume that handle 30 is operated to movie trolley -50, vorthat the ship yaws to an unusual extent,

moves beyond contact 76 and that contact 7 0 vmoves beyond contact 72 or73. Contact 68 still engages co tact 5 1 or '52. Assumethatcounterclockwise movement of Y the ship .is necessary to bring it to itsnew course. A circuit is established which includes lcontacts 68 and 51,rela i s 81 and 82to coil 83'to drive the rudder cloc Wise and turn thevship counterclockwise. .When the rudder' reaches limit.- in contacts 96,it breaks the 'circuit through coil 83 by energizing relay 81. -As theship starts to turn counterclockwise, however, no

circuit is established through coil 90 to return 41j `the rudder, as inpreceding-cases, since contact 69 is oif contact 76. The .ruddertherefore, holds its 'extreme'positiom causing the ship to turn rapidlyand continuously, until,

course,

tact 7 6, and thereafter the device operates as in the other cases-j Therudder is returned 'before the ship reaches its. course, allowing themomentumof the ship to bringit to its course.`-

When-the .ship is toebe turned -clockwise, the lowerset' of relaysvenergizes coil 9() to drive the rudder counterclockwise, until itengages stop 97 to energize relay 88 and break the circuit. -Whencontact 69 engages contact 76, the upperset of relays is'effective toenergize coil 83 Yand return the rudder. It is thus apparent that forsmall deviathe device operates as in cases the rudder outwardly adistance proportional to the deviation, and as soon as the Shipstartsback, the rudder is returned, shipbeing suicient to carryr it toits course.- For large' deviations, however, the rudder is held inextreme position, until the ship approaches Aits course.

or yawin alarm may and thus permit a y .such that contact 69,-

'meclianism is contact 69 engages con-- tervaL Thereafter,

1', 2 andVV Before the shipreaches its course, the rudder is returnedand the momentum thus imparted is suiiicient to bring the ship to itscourse.

It Will also be apparent that it-is imniaterial how trolley comes-intoengagement with the contact strips, whether through yaw- 'l .of energy99 may be provided in circuit with trolley 50 and contacts 71, so thatan alarm is sounded whenever such unusual turning.

of the ship takes place, cause trol ey 50 to engage said contacts. The

thus serve to warn against unusual atmospheric orv tidal conditions orfaults arising from the ship proper.

The motor 84 maybe arranged to control a steering mechanism, such as atelemotor of the usual type. Thus tlie`motor shat 110 may operate va'pinion 111 which engages two as will l racks 112 and 113 on oppositesides thereof.

vSaid racksoperate 'as plungers in cylinders 114, 115, so that rotationof pinion 111 Will cause one plunger to move inwardly in its cylinderand the' other plunger to move outuardly. This causes a displacement ofthe 'fluid to one side which is transmitted byV pipes 116, 117 connectedto cylinders 114, 115, respectively, to the opposite sides of thesteering engine 120, 121, whichis geared tothe sector l22,integral withthe rudder. Further details of the steering' engine are not essentialvfor the purposes of disclosing vthe present invention, since suchenginesa're standard commercial units and -well known in the art.

It will be observed that it is the rudder ,that controls the coursecontrol mechanism by a follow-'up mechanism. This follow-up thereforeindependent of the steering engine used to operate the rudder, and henceall errors arisingin the telemotor. its gearing transmission, etc. Vareeliminated so far as the course control mechanism is concerned.

Motor 65 is a' series\ motor, one of the characteristics o f which isthe picking up'in speed the longer it runs,'witliin afgiven inas thecounter E. M. F. builds up, the speed diminishes. This action .of themotor isdesirable because for small movements of' the rudder only theinitial, comparatively slow speed of the motor is utilized, but Wherethe rudder is to be operatedthrough greater distances, the motor picksup speed the longer it rotates and thus drives the rudder more rapidlythan for small angular distances.; It may occur, however,

that the rudder isopera-ted through so great an angular distance thatthe motor rotates long enough for the second phase, i. e., thediminishing speed, to set in. To prevent such diminution in speed, theremay be provided a relay 125, the coil 126 vof which is in series e witha resistance 127 the inotoincircuit.

When the counter E. M. F. builds up, relay 125 is operated to shortcircuit resistance-127 and thus increase the speed of the motor. .Thesystem may be made sensitive by employing a plurality of relays similarto 125 adapted to be operated successively to cutout an increasingamount of resistance and thus If a vessel yaws equally from .side toside,

the rudder will be operated through equal angular distances to eitherside of the true course, in orderlto counteract these. yawing movements.Due, however, to such forces as the direction of the wind, the variationin the revolutions of the propellers in multiple screw ships, the tidesand currents, the vessel is often continually forced off` its course inone direction. The rudder instead of being operated equally to eitherside of the true course must now be operated through a segmental portionwhose central axis Iis considerably to one side ofthe true course, thuscausing the ship to follow a new course which 'slightly deviates fromthe true course. This variation of the mean position of the rudder fromthe true mean position (i. e.,`th e true course of the ship) is termedthe helm- In the present invention as hereinbefore describe-d, tocounteract these additional forces, the rudder would be thrown outwardlyan angular distance sufficient to bring the ship back to its course.'Ihe rudder would be returned shortly before the ship reached itscourse, withthe result that the ship would again be turned.I olf itscourse by these extraneous forces, necessitating operation of the rudderin the same direction again. There thus results a continuous yawingmovement of the ship mostly to one side of the true course, and to avoidrepeating this process as long as the extraneous forecsare operative,means are provided for preventing this lyaw by Y changing theyrelationship which exists between the compass and the rudder andautomatically determining the helm, i. e., .estab-v lishing a' virtualcenter which 1s such a position of rest of the rudder varying from thetrue center position, as will be sufficient to counteract ,the effectsof the extraneous forces and keep the ship on its true course. In otherwords, where heretofore the indications of the ships course on thecompass corresponded to the true central position of the rudder, thesame indications will correspond to the mean position of helm.

through link lrelative to segment'155.

For automatically determining the mean position of helm, the rudder 46(see Figs. 5 to 8) is connected by means of an adjustable link to asegment 151 mounted upon a vertical shaft 152 journaled in a boss 153,forming part ofa base 154. Fixed upon said shaft between segment 151 andboss 153 is a second and larger segment 155. The latter ca'rriesoperating links 156, 157 extending therethrough, and preferably havingrollers 158 at their lower ends, which are normally pressed intoengagement with base 154 by springs 149. Said operating links areadapted to cooperate with cams 16() and 161 positioned on said base,said links andeams being so' positionedthat equal angular movements ofsegment 155 to either side of center line Y-Y will causeoperating link156ito engage cam 16() or operating link 157 to'engage cam 161 to forcethe respective'link upwardly and operate a ratchet 165 or an oppositelytoothed ratchet 166, respectively. Said ratehets are fixed to the endsof a shaft 168 journaled upon segment 155 and having akwor'm 170 formedthereon meshing with a rack 171 on the peri phery of segment 151. Itwill thus be seen that rudder 46y is movable integrally with segmenty155, as well as relatively thereto, 150, worm 170 and gear 171 and anymovement of the rudder will` cause corresponding movement of segment155. Assuming that there are no extraneous forces,

the rudder 46 moves equal angular distances to either side of line X-Xto counteract yawing movements of the ship. Segment 155 therefore alsomoves equal angular distances to either side of line Y-Y. If thesedistances are very small, links 156, 157 will not reach cams 159, 160,but if the distances are comparatively large, each operating link willengage its respective cam. Operating link 156 will engage cam and beraisedV against the action of spring 149 to cause a pawl member 175carried at the upper end of the link to engage ratchet which is thusoperated to rotate worm and so move rudder 46 relative to segment 155.As the rudder moves to the opposite sidel of line X-'-X, link 157engages cam 161 to cause a pawl 180 carried hy said link to operateratewt 166 in the reverse direction to ratchet 165 and so restore theoriginal relative positions ofthe rudder -and segment 155. Springs 177may be provided to engage the pawls, and move them out of engagementwith the ,ratchets when the operating links are lowered.

Assume, now, that extraneous yforces arev acting upon the ship,necessitating in'vement of the rudder toward the right,counter-clockwise, to bring the ship back to its course. In so movingthe rudder to the right, link 156 engages cam 160 to operate ratche166-and move segment 151 and rudder 46 to the right its course, the rudderis returned until seg--` When the ship nears of the ru ation ofthe'rudder to act the uextraneous ment 155 is on its center line Y-Y,but the rudder is now positioned slightly to the right of X-X. Insteadof swinging to the left of line Y-Y, as in ordinary yawing, theextraneous forces again move the ship off its course, before link 157has engaged cam 161 to operate ratchet 165, necessitating operation ofthe rudder to the right to operate ratchet 166 again. The continuedoperation of the ratchet 166 moves the rudder continuously to the rightof center line X--X and relative to segment 155, thus giving the ruddera permanent set or helm ofi' .its 'true center suficient to counteractthe effect of the eX- traneous forces. The ship is thusheld upon itscourse except for those yawing movements which give rise to equal-angular movements dder to either side of its mean position of helmindicated by line' Z-Z in Fig. 8, causing equal operation` of ratchets165 and 166 -to maintain therelative positions of the rudder and segment155. The lineZ-Z is the new or virtual center position of the rudder andthere is thus avoided the necessity of re )eatedly swinging the rudderfrom line X to line Z-Z, to counterforces which necessitate thesettingofhelm. Large yawing movements of the craft are thereforeprevented by this automatic helm positioningdevice.

If extraneous forces should now operate on the ship, to turn it off itscourse in a direction so as to necessitate repeated operthe left,clockwise, ratchet 165 will be operated' more frequently than ratchet166 to move the rudder to the left relative to segment 155. Thus, anyextraneous force which would tend to throw the ship steadily off itscourse is automatically compensated by the positioning of helm effectedby the unequal operation of -ratchets 165 and 166, to counteract suchforce, so that steering of the ship may progress as if such force werenot present. The mean position of helm -is thus the base linefrom whichthe steering mechanism operates. The device is thus constantly settingitself to the scientifically accurate virtual center or meanposivariations.

tion of helm for maintaining the true course. A v

The adjustable link 150 comprises two portions connected by aturn-buckle 190 whichv ermits the initial relative positions of therudder and the segment 155 to be adjusted to take care of suchvariations as are due to the particular vessel, or any other' known Byreferring tothe graphs of Fig. 9, the principles of navigation embodiedin this in-` l,vention may be illustrated. In all of these graphs therudder movements are recorded. Referring to graph 1, it will be seenthat theY rudder was operated for small angular distances (shown hereas'about 2) which would correspond to movements between contacts 86steadily to the right.

' (shown here as ap der, are here mounte ,way

lof the rudder varies and 91, or sufficient to counteract ordinary yaw.The aph shows an occasional rudder movement eyond these points, but onthe `whole the yaw takes place eq;i lly to either sidev of the actualcenter X- The condition where an extraneous force sets in to turnthecraft constantly o' its course is illustrated in graphs 2 a force isacting to turn the craft constantly toward the right. Graph 2 is arecord of the rudder movements which are due `to an inexperiencedhelmsman, or to automatic steering means which makes no provision forautomatic determination of helm. Between the points A and B the vesselyawed nornally. Thereafter, forces tended to turn it off its courseconstantly toward the right. The helmsman or automatic steeringmechanism hereinbefore mentioned threw the rudder outwardl (to a pointhere shownas 8) and broug t the craft back to its course, Whereupon therudder was returned to center position X-X, but no sooner did the craftreach and 3, where its course, than it was turned off toward the rightagain, necessitating operating the rudder outwardly again, through 8 inthe same direction. This operation was continued as long as the saidforce acted to turn the ship 3, there is illustrated the manner in whichan automatic steering mechanism equipped with the automatic mean helmdetermining mechanism of this invention met the situation or conditionpresent in graph 2. The portion A--B corresponds to the portion A--B ofgraph 2,. lThe portion B-C, however, illustrates the operation of givingthe craft helm. Instead'of returning the rudder (which has been swungoutwardly the same 8 as in (graph 2) to center line X-X, it is stoppedshort of said line by constantly increasing angular distances intil anew center line position wasA found. In the graph this line is shown as6 to the right of thev actual center X--X, indicating that lbyoffsetting the rudder 6, thet force which tends to turn the craftsteadily off its course is neutralized. Thereafter, ordinary to and fromovements of therudder roximately 2) takes lace to either side of t evirtual center Z- instead of the large rudder movements (about 8) ingraph 2 under the same conditions. This of course also means that the amlitude of the yaw is correspondingly reduced.'

The follow-back contacts, which in the diagrammatic representation ofFig. 4 are shown as engaged directly. b the bar on the rudon base 154and so positioned as to be engaged bythe bars 178 and 179 on the segment155, since the latter alsmaintains the same initial position relativeReferring to graph according to the mean position of helm. Said bars178, 179 are l to said contacts, while the initialposition l spaced inplanesone above the other. The contacts 91, 93, 95 and 97 are arrangedin the path of bar 178, while contacts 86, 92, 94 and 96 are arranged inthe path of bar 179. L In accordance with the provisions of the patentstatutes, I have' herein described the principal of operation of myinvention, together wlth the apparatus, which I now consider torepresent the best embodiment thereof, but I desire to have itunderstood'that the apparatus shown is only illustrative and that theinvention can be carried out by other.

combination with the compass governed con-l troller and rudder, of meansresponsive to' persistent yawing movements ot the ship in one directionfrom the course, and means operated thereby for changing the relationbetween the compass controller and rudder to centralize the oscillationsof the controller and rudder. i, v

2. In combination with a steering mechanism of a dirigible craft4including a rudder, a control member actuated in accordance withmovements of said craft on opposite sides of its course, adjustablemeans connected between said rudder and said member whereby the relationof said rudder with respect to said member and said craft may be varied,and means for automatically actuating said adjustable means uponpersistent movements of said member to one side of its cent-ral positionto change the normal relationship between the rudder and control memberfor the purpose specified.

3. In combination with the steering mechanism of dirigible craft, meansfor counteracting movements of the craft to either'side of its courseand means operated by the unequal `movements of the craft on oppositeSides of its-course for automatically altering the mean position of therudder to equalize said movements.

lll The combination with the automatic steering mechanism for dirigiblecraft including a compass and automatic means governed thereby forvactuating the rudder, of means for altering the relationship between thecompass and rudder, and automatic means brought into action bysuccessive unequal movements of steering mechanism to one'side of theneutral position for operating said first-named means.

5. The combination with automatic steering mechanism for dirigible crafthaving a ments of the craft on opposite sides of itsv course foroperating said member, an intermediate adjustable member connectmg saidfirst-named member and rudder, and means actuated by unequal excursionsof said member for operating said adjustable memberto change therelation between the rudder and controller for the purpose specified.

G. The combination with automatic steering mechanism for dirigiblc crafthaving a compass governed controller and a rudder,

of means for preventing deviation from the' course by side winds and thelilre, said means comprising a member mo.'ably connected to said lcraft,adjustable nieans connecting said member and rudder, and means'actuatedin accordance with unequal movements of the craft on opposite sides ofits course for operating said adjustable means to change the normallyfixed relationship between the rudder and controller. l

7. 'The combination with automatic steer'- ing niechanism for'dirigiblecraft having a rudd .-r, o'f means for automatically determining themean. position of helm, said means comprising a member movably connectedto said rudder and craft, and means whereby unequal movements of saidmember on opposite sides of its central position operates said memberand rudder to set a new'base line for said rudder.

8. The combination with automatic steering mechanism for dirigible crafthaving a` rudder, Aof means for reducing the rudder movements, saidmeans comprising a member movably connected to said rudder and craft andmeans whereby unequal movements lot' said member on opposite sides ofits base line operates said `member-and rudder to set a new base linefor said rudder.

9. The combination with automatic steering mechanism for dirigible crafthaving a rudder, of means for automatically determining the meanpositionof helm, said means comprising a member movably connected tosaid rudder and craft and means whereby unequal movements of said memberon opvpositeI sides of its base line operates said member and rudder toset anew base line for said rudder, the deviatlon of said new base lin'efrom the old base line being m proportion to the degree of inequality ofsaid rudder f movements. f

10. In automatic steering mechanism for dirigible craft having a rudder,the combination with a' master controller of means for altering therelation between the rudder and controller to alter the neutral positionof the former, said means comprising mechanism whereby unequal movementsof said rudder on opposite sides of its neutral position moves therudder with respect to said controller in a direction of said greaterrudder .movements from said position.

11. In automatic steering mechanism for dirigible-craft having a rudder,the combination with a master controller of means for alteringtlierelation between the rudder and controller to alter the neutralposition of the former, said means comprising mechanism whereby unequalmovements of said rudder on opposite sides of its neutral position movesthe rudder with respect to said controller in a direction of saidgreater rudder movements from said neutral position.

12. The combination with automatic steering mechanism for dirigiblecraft having a rudder, of means for reducing the rudder movements, saidmeans comprising means for offsetting the neutral position of saidrudder with respect to said 'automatic steering mechanism when the`rudder is continuously operated more to one side of its normal neutralposition than to the other and means for offsetting the neutral positionin the 0pposite direction when the rudder is continuously operated moreto said other side of its said normal neutral position than to the'first side, for the purpose specified 13. The, combination withautomatic steering mechanism for dirigible craft having a rudder, ofmeans for automatically determining the mean position of helm, saidmeans comprising a member connected to said rudder, a second memberadjustably connected to said first-member, and means for operating saidirst member relative to said second'member, when the rudder operates toone side or the other of its base line, to move said first member andrudder in a corresponding direction relative to said second member andOifset the base line in said direction.

14. The combination witlr automatic steering mechanism for dirigiblecraft having a rudder, of means for automatically determiningv the meanposition of helm, said means comprising a member connected to saidrudder, a sec-ond member adjustably connected to said first member, andmeans for operating said first member relative to said second member,when the rudder operates to one side or the other of its base line, tomove said first member and rudder relative to said' second member tooffset the base line.

15. The combination with automatic steer.

ing mechanism for dirigible craft having a ',rudder, of means forautomatically 4ing` the mean position of helm, said means comprising amember connected to said member adjustably connectdeterminrudder, asecond ed tov said first member, a plurality of mechanisms vformovingsaid first, member and rudder relative to said means for operatingone of said mechanisms to oset'the base luie of the rudder 1n one secondmember anddirection when said rudder is operated to one side of saidbase line and for operating the other of said mechanisms to offset thebase line in the other direction when said rudder is operated to theother side of said base line.

1.6. The combination with automatic steeringmechanism'for dirigiblecraft having a rudder, of a member connected to said rudder, a secondmember adjustably connected to said first member, means for varying therelation between said two members, including a plurality of mechanismsfor moving said rst member4 and rudder relative'to said second member,one of said mechanisms operating said means to' oset the base line ofthe rudder in one direction and the other of said mechanisms operatingsaid means to offset the base line in the other direction and means for'operating one of said mechanisms when said rud der is operated to oneside of said base line and for operating the other of said mecha-- nismswhen said rudder is operated to the other side of said base line.

17. The combination with automatic steering mechanism for dirigiblecraft having al rudder, of a member connected to said rudder` a secondmember adjustably connected to said first member, gearing between saidmembers, a pluralityof mechanisms for operating said gearing to movesaid-first member .and rudder relative to said second member, one ofsaid mechanisms operating said gearing to offset the' base line of therudder in one direction and the other of said mechanisms operating saidgearing to offset the base line in the other direction, said mechanismseach' comprising'a pawl and ratchet and an oper- 4 ating member carriedby said seoondmember for operating said pawl and ratchet and means foroperating one of said mechanisms when the rudder is operated to one sideof the base line and for operating the other of said mechanisms when therudder is operated to the other side of said base line.

18. The combination with automatic steering mechanism for dirigiblecraft having a rudder, of' means for automatically determining the meanposition of helm, said means comprising a member connected to saidrudder, asecpnd member adjustably connected to said first member,gearing between said members, a plurality. of mechanisms for operatingsald gearing to move said member and rudder relative to said secondmember, one of said mechanisms operating said gearing to oset the baseline of the rudder in one direction and the .other o fsaid mechanismsoperating said gearing to oset the base line inthe other direction, saidi'nechanisins` Jeach,comprising; a pawl and ratchet and an operatingmember carried by said second memberfor operating said pawl and ratchetand a plurality of cams, eachpof said operating members being adaptedtov engage one ofl said cams to be operated thereby when said rudder isoperated to one side or the other of the base line. i v

19. 'The combination withv automatic steering mechanism for-diiigiblecraft having a rudder, a membei' m'ovably connected to said rudder andcraft, and means actua-ted in accordance with the movements of the crafton opposite sides of its course for operating said member andsettingsaid rudder, said member being adjustably connected to saidrudder to vai'y the position of the rudder.

- relative tothe steering mechanism.

erned -thereby for actuating `the rudder, of:

20. In an automatic steering mechanism for dirigible craft having arudder and course indicating means. means for setting said rudder inpredetermined relation to said indicating means, and means controlled bythe movements of the rudder for automatically changi'ng thelrelationship between said indicating means and said rudder.

21A. In an automatic steering Imechanism for dirigible craft having arudder land course indicating means, said rudder being normally set inpredetermined relationto -said means, `means-'whereby said rudder isoperated to counteractmovements of the craft off its course,'and meansfor -,automatically changing the relationship between said l afollow-back systembetween the rudder and said means, and means foraltering the position of the rudder with respect to saidfoliow-baclcsystem to change the relation between tliecompass and therudder.

24. In an automaticy steering device, a means 'for preventing deviationof a ship from'itscourse comprising means responsive to yawing of theship to oneside of the course, and means operated by said second namedmeans forcorrecting the relative positions of the controller and rudderto maintain the ship on its original course.

Q5. In an automatic steeringdevice for ships, a mea-ns for preventingthe deviation 'of a ship from its course, comprising the conibinationwith the compass and rudder, ofurieans responsive to yawi'ng of".theship to one side of its course, thereto for 'changing the relationbetween the compass and rudder to maintain the ship on its originalcourse.

and means responsive 26. In an automatic steering device, a means forpreventing deviation of a ship from its course, comprising meansresponsive to yawing of the ship to one side of the course, andautomatic means operated by said second named means for correcting thesetsignature.

ELMER A. SPERRY, JR.

